Process and apparatus for burning sulphite liquor

ABSTRACT

Sulphite liquor, for example, magnesium bisulphite liquor is burned in a combustion chamber which forms part of a steam generator. The burning of the liquor is accomplished at pressures of between 5 to 25 atmospheres excess pressure and at a temperature of about between 80* and 100* C. The combustion chamber should preferably have constant height dimensions with a depth of at least 1.5 and at the most 5 meters. The combustion chamber is charged in quantities so as to correspond to a specific cross sectional load of between 3 X 106 to 5 X 106 kcal./m.2h.

United States Patent lnventor Appl. No.

Filed Patented Assignee Karl-Heinz Wirths Munich, Germany Mar. 13, 1970 Nov. 9, 1971 L 8: C Steinmuller G.m.b.H. Gummersbach, Germany PROCESS AND APPARATUS FOR BURNING SULPHITE LIQUOR 6 Claims, 2 Drawing Figs.

US. Cl 122/7 C, 1 10/7 R Int. Cl. F22b 1/18 Field of Search 23/48, 277;

[56] References Cited UNITED STATES PATENTS 2,213,052 8/1940 Rosencrants et al r. 122/7 2,258,467 [0/1941 Owens 122/7 2,739,878 3/1956 Jolley 23/48 X 3,373,704 3/1968 Jung 122/7 X Primary Examiner-Kenneth W, Sprague Atmmey- McGlew and Toren PATENIED NOV 9 197: 36 1 8571 SHEET 2 0r 2 I IV VE N 70E KARL HE/NZ W/R THS PROCESS AND APPARATUS FOR BURNING SULPHITE LIQUOR FIELD OF THE INVENTION The invention relates to a method for burning sulfite liquor,

particularly magnesium bisulflte liquor in a steam generator.

BACKGROUND INFORMATION AND PRIOR ART In prior art methods and apparatus for burning sulfite liquor, for example calcium or magnesium bisulfite liquor, the liquor is atomized at pressures of about 3 to 5 atmospheres excess pressure. Steam is the customary atomizing agent. The temperatures of the liquors to be burned are in the known procedures between about 1 and l C. At the liquor temperatures with which the prior art procedures are carried out, undesired and substantial contamination of the structural elements which are contacted by the liquor take place. It is thus known in this art that crust formations on the structural elements of the plant set in which cause undesired work stoppages. In particular, crusts are frequently formed in the pipelines and preheaters. Particularly disadvantageous are the crusts which have a tendency to form on the atomizing devices. These crusts negatively affect not only. the atomizing procedure proper but also the combustion and thus the recovery of the combustion product. It is well known in this art that the dreaded crust formationon the structural elements which come into contact with the liquor generally requires, dependent on the particular type and quality of the liquor, frequent cleaning or even replacement of the respective structural elements. This in turn has an unfavorable influence on the combustion procedure, particularly if individual burners have to be replaced during the combustion process.

Experience has demonstrated that, from a practical point of view, the prior art atomizing pressures of between 3 to 5 atmospheres excess pressure in many instances do not cause the type of atomization as it is desirable for performing the combustion in a satisfactory manner and for obtaining recoverable residues of satisfactory quality.

It has been attempted to overcome the disadvantages referred to by increasing the amount of steam which is used for the atomization. However, it has been found that a larger amount of steam does not obviate the drawbacks referred to. While it is true that larger amounts of steam cause better atomization, it must be considered, however, that this also results in an increased amount of flue gas which in turn lowers the combustion temperature and thus the quality of the residues to be recovered. V

SUMMARY OF THE INVENTION It is a primary object of this invention to overcome the drawbacks of the prior art procedures referred to and to provide a procedure for burning sulfite liquor which is exceedingly simple to carry out, which results in optimum conditions for the burning and by means for which residues of superior quality are obtained.

Another object of the invention is to provide a procedure of the indicated kind by means of which the dreaded crust formation is substantially prevented or at least drastically minimized.

Still another object of the invention is to provide a steam generator plant which contains a combustion chamber forming a unit with the steam generator, the chamber being of a construction and dimension so that upon proper operation the above objects are readily obtained.

Briefly, and in accordance with the invention the burning of sulfite liquor is effected at pressures between 5 and atmospheres excess pressure and at a temperature of about between 80 to 100 C., in a combustion chamber which forms a unit with the steam or vapor generator proper.

The combustion chamber which thus is a part of the vapor generating plant and in which the inventive burning procedure is carried out should have a substantially constant height dimension and should have a substantially constant height dimension and should be charged with a specific cross-sectional load of between 3X10 to 5 l0 kcal./m.hr. Experiments have indicated that the best results are obtained if the depth of the chamber is at least 1.5 and at the most 5 meters.

By performing the combustion procedure in the indicated manner and in a combustion chamber of the indicated kind, the disadvantages of the prior art procedures are effectively overcome. Contaminations such as crust formation on those structural elements of the plant which come into direct contact with the liquor are effectively avoided. Further, due to the atomization of the liquor at a substantially higher pressure of, for example, 10 atmospheres excess pressure, an atomization degree is obtained without increasing the amount of steam, which leads to a most satisfactory combustion and results in recoverable combustion residues of superior quality. The liquor temperature, which is lower than that employed in the prior art procedures, does not require any preheating during the operation of the plant.

For an understanding of the principles of the invention, reference is made to the following description of a typical embodiment thereof as illustrated in the accompanying drawings.

FIG. 1 is a somewhat diagrammatic representation of a steam generator comprising a combustion chamber in accordance with the invention, while,

FIG. 2 is a flowsheet illustrating a preferred embodiment for operating the plant.

Referring now to FIG. 1, a vapor or steam generator is generally indicated by reference numeral 100. Since the structure of the steam generator proper does not form part of the invention, no further description of the steam generator in included herein. In accordance with the invention, the steam generator 100 includes a combustion chamber generally indicated by reference numeral 150. The combustion chamber is defined by walls 102, including a roof portion 104 which are lined with a tamped lining or tamping mass indicated by reference numeral 103. The lower portion of the combustion chamber 150 is open as indicated at 4 and communicates with the flue space 105 of the steam generator proper. The roof or ceiling portion 104 of the combustion chamber 150 is traversed by nozzles 106 and 107 for the supply of combustion air. In the preferred embodiment of the invention, the nozzles 106 and 107 are inclined relative to the lateral walls of the chamber 150. The burners 10 (only one visible in FIG. I) are arranged in the lower portion of the combustion chamber 150 and are supplied with the liquor to be burned and the atomizing steam in a manner known per se. The atomized liquor,

whic hmay be admixed with oil in addition to the steam, thus is sprayed in an upward direction, the combustion air entering through the nozzles 106 and 107 flowing in opposite direction. The combustion gases which are formed as a result of the combustion are discharged through the open lower portion 104 to exit through the flue of the steam generator while the solid residues collect at the bottom of the generator.

The height dimension of the combustion chamber should preferably be substantially constant while the depth of the chamber is between about L5 to 5.0 meters. The chamber is charged at a cross-sectional load of between about 3 l0 to SXlO kcaL/mFhr.

FIG. 2 is a flow diagram of the overall operation of the plant which may be briefly described as follows:

The liquor to be atomized and burned is contained in a storage receptacle 1 and flows through a valve controlled conduit 21 through the changeover-valve 2 and from there through conduit 22 into the crust breaker 3. Solid matter is thus crushed in the crust breaker 3. The liquor leaves the crust breaker 3 through conduit 23 and is pumped by pump 4 through conduit 24 into the homogenizer 6. Any remaining solid matter is comminuted in the homogenizer 6 to a particle size of less than l mm. The homogenizer may also be supplied with oil which is fed by the dosage pump 7 through conduit 26, the oil flowing through the dosage pump 7 from a supply source not shown through conduit 28. The supply of oil through the homogenizer is not absolutely necessary but is to be recommended in order to equalize pronounced heat value fluctuations of the liquor. The liquor or oil-liquor mixture flows then from the homogenizer 6 through conduit 29 and changeover-valve 8 to the control valve 9 of the liquor burner 10. The atomizing steam required for the atomization of the liquor is supplied through line 31 fitted with control valve 11. It will be noted that the circuit so far described is duplicated on the flow sheet and that each of the elements is present a second time. Thus two pumps 4, two homogenizers 6 and two burners l and two breakers 3 are provided. By properly setting the two changeover-valves 2 and 8 the liquor from the storage receptacle 1 will thus flow through one or the other circuits. If the liquor flows through one of the circuits, the second circuit can be flushed with acidic condensate which enters through valve controlled conduit 33 and exits through line 40.

The plant also provides a liquor preheater in which the liquor may be preheated to a temperature sufficiently high so that the temperature of the liquor in the storage receptacle 1 will be about 80 to 100 C. It will be noted that the preheater 5 and the receptacle 1 are in circulating communication. The liquor preheater 5, however, is only used when the steam generator is at rest. The preheater may be heated by steam or in electrical manner. If the steam generator is operating, the liquor is obtained at a temperature of about 90 C. and no preheating is necessary.

What is claimed is:

1. In a method of burning sulfite liquor in a steam generator,

wherein liquor is injected into a combustion chamber and atomized by steam, the improvement which comprises that the liquor is burned at pressures between about 5 to 25 atmospheres excess pressure and at a temperature of about between to l00 C.

2. The improvement as claimed in claim 1, wherein said combustion chamber is part of said steam generator.

3. The improvement as claimed in claim 1, wherein said sulfite liquor is magnesium bisulfite liquor.

4. The improvement as claimed in claim 1, wherein said combustion chamber has a substantially constant height dimension, said chamber being charged with liquor so as to correspond to a specific cross-sectional load of between about 3X10 to 5X10 kcal./m. hr.

5. The improvement as claimed in claim I, wherein said combustion chamber has a depth of at leastv 1.5 and at the most 5 meters.

6. In a steam generator, a combustion chamber suitable for burning sulfite liquor and comprising in combination wall means defining said combustion chamber, burner means located at the lower portion of said wall means and having means for passing sulfite liquor and atomizing steam therethrough, whereby said liquor is atomized in an upward direction, nozzle means provided in the upper portion of said wall means for introducing combustion air into the upper portion of said chamber, exit means in the lower portion of said chamber for exit of combustion gases, said chamber having a substantially constant height dimension and adapted to be operated at a specific cross-sectional load of between about 3X10 to 5X10 kcaL/mFhr. 

2. The improvement as claimed in claim 1, wherein said combustion chamber is part of said steam generator.
 3. The improvement as claimed in claim 1, wherein said sulphite liquor is magnesium bisulphite liquor.
 4. The improvement as claimed in claim 1, wherein said combustion chamber has a substantially constant height dimension, said chamber being charged with liquor so as to correspond to a specific cross-sectional load of between about 3 X 106 to 5 X 106 kcal./m.2hr.
 5. The improvement as claimed in claim 1, wherein said combustioN chamber has a depth of at least 1.5 and at the most 5 meters.
 6. In a steam generator, a combustion chamber suitable for burning sulphite liquor and comprising in combination wall means defining said combustion chamber, burner means located at the lower portion of said wall means and having means for passing sulphite liquor and atomizing steam therethrough, whereby said liquor is atomized in an upward direction, nozzle means provided in the upper portion of said wall means for introducing combustion air into the upper portion of said chamber, exit means in the lower portion of said chamber for exit of combustion gases, said chamber having a substantially constant height dimension and adapted to be operated at a specific cross-sectional load of between about 3 X 106 to 5 X 106 kcal./m.2hr. 